This invention in general relates to pressure sensors for use in combination with a compressed air tank, and more particularly, to a protection system that helps maintain proper operation of the sensors. In particular, this application discloses a sensor and protection system for use therewith that is attached to a compressed air tank for a large construction vehicle for removing moisture that may result in freezing, corrosion, or plugging of the sensor.
In modern construction vehicle applications, compressed air is used to operate several types of components. In these types of applications, it is preferable to provide a compressed air tank that can store a relatively large supply of compressed air for the several pneumatically actuated devices. For example, a modern construction vehicle will have several operations or features that will require compressed air in order to operate. Thus, a compressed air tank is normally provided that will supply air to the various items that require it.
A compressor normally intermittently charges the air tank until a preset pressure is reached, at which time the compressor may be disengaged. The tank is maintained at a preselected pressure until the various loads deplete air such that the pressure within the tank falls below a preset pressure, and the compressor is then reactivated to recharge the tank. In these prior devices, it is known to utilize various types of pressure sensors that monitor the pressure within the tank and act in various ways to either automatically shut off the compressor or signal an operator that a predetermined maximum pressure has been reached. In several of these prior art devices, the sensors are pneumatically operated, and the pressurized air within the tank acts directly upon a diaphragm portion of the sensor in order to actuate it.
Problems sometimes arise with these systems, particularly the ones that act to give a visual signal to an operator. In many of these environments, operators are required to do a number of operations and do not have time to closely check the status of the sensors. It is important that the operator has an indication that the pressure within the tank is approaching the preset maximum, and it is also important that the operator has an approximate idea of the pressure within the tank at any point in time. A numerical dial is not normally satisfactory for this purpose, since the operator may be remote from the location of the dial and also may lack the time to study the dial closely in order to make a reading.
A problem may arise with these types of pneumatic sensors due to vapor impurities within the air in the tank. In compressing air, water vapor will condense, and water droplets will form and travel along with the compressed air. Additionally, in a lubricated compressor, there is usually some oil entrained with the compressed air stream. This water or oil can contaminate the sensors, leading to freeze-ups, corrosion and plugging of the sensors. This is undesirable, since it may prevent normal operation of the sensors.
It is, therefore, an object of the present invention to provide a sensor and sensor protection system that will prevent moisture from reaching the sensor and will retain the sensor dry and properly operating.
Moreover, it is an object of this invention to achieve these characteristics with a sensor and sensor protection system that is inexpensive and requires relatively few moving parts.
These and other objects are addressed by the present invention.